Method fob the recovery- of



Patented Ann 17, 1934 UNITED STATES METHOD FOR THE nnoovsnr 0F nLooHoLs CONTAINING Moan THAN FOUR CARBON ATOMS William Engs and Richard Moravec, Berkeley,

Calif., assignors to Shell Development Company, San Francisco, Calif, a corporation of Delaware No Drawing. Application June 9, 1931, Serial No. 543,238

16 Claims.

This invention relates to a process for the production and segregation of secondary alcohols containing more than four carbon atoms and is more particularly concerned with the avoidance of decomposition of the secondary alcohols.

With the initiation of cracking operations in the petroleum industry, attention has been directed to the possible uses of the gases arising from the cracking operations. These gases conan a substantial amount of olefines and their olefinic content may be increased by practicing the cracking process under certain conditions as may be ascertained from the art. Similar olefine-containing gases may be derived by the pyrogenetic treatment of peat, coal, oil shales and like carboniferous natural materials.

These olefine-containing gases have been utilized to produce secondary alcohols according to various methods known to the art. One procedure has been to fractionate the olefine-containing gases to obtain a relatively pure cut containing paraffin and olefine hydrocarbons of the same number of carbon atoms which is thentreatedwith a selective absorbent to remove the highly reactive isomers hereinafter termed tertiary-base olefines. The unattacked remainder of the fraction is then reated with an esterifying agent such as sulfuric acid of sulfating strength and subsequently diluted with water until the acidity of the solution isabout 15% H2504 or less, followed by distillation to effect the removal of the hydrolyzation products. Such procedure entailed a consequent loss of concentrated acid due to the dilution with water.

We have discovered that secondary alcohols can be prepared simply and economically from olefine-containing gases of the type mentioned heretofore by hydrolyzing the esters of the olefines contained in the desired fractions in relatively strong acid solutions at temperatures below the distillation temperature of the secondary alcohols, i. e., below the boiling point of the constant boiling mixture of the secondary alcohol with water at normal pressure, although our invention is not limited thereto as it may be practiced with any hydrocarbon mixture comprising essentially olefines of five or more carbons atoms, such as amylene, hexylene, etc., preferably one from which the tertiary-base olefines have been removed.

The preferred initial material is substantially stripped of hydrocarbons containing less than five carbon atoms and suitably fractionated into fractions containing hydrocarbons of the same number of carbon atoms per molecule. In certain instances, it will be difficult to remove traces of higher and lower carbon compounds, but their presence is not detrimental to our process. We prefer to practice our process with a substantially pure fraction of hydrocarbons containing the same number of carbon atoms per molecule.

The hydrocarbon fraction is then preferably treated with a selective absorbent to remove tertiary-base olefines. Polybasic acids, of which sulfuric acid and phosphoric acid are typical, are suitable as are hydrochloric acid and sulfonic acids of benezene and its homologues. The remainder of the fraction is then esterified with a suitable acid such as the polybasic acids heretofore enumerated. When sulfuric acid is employed, the strength of the acid should be above 75% H2SO4, preferably between 80% to 100% H2804. Any parafiin hydrocarbons present are relatively inert to the acid under the sulfating conditions and may be removed from the acid solution of the esters after stratification as the esters are miscible with the acid and both the acid and esters are relatively immiscible with the paraflin hydrocarbons.

The acidity of the acid solution of the ester, for example, arnyl hydrogen sulfate, is adjusted to below 35%, preferably between about 20% to 30% acidity. This relatively strong acid solution is then heated in any suitable manner to a temperature below that at which the secondary alcohol, for example, secondary amyl alcohol, distills over. The time required for heating the acid solution is dependent on the character of the ester, the concentration of the ester, the acidity of the solution, the character of the acid, the temperature, etc., and varies with different combinations of the enumerated variable factors. In practice, the desired set of operating conditions would depend on the economics of the plant operating the process and accordingly our invention is not restricted to any specific temperature or period of heating but resides in the heating of a relatively strong acid solution of an ester to a temperature below that at which the corresponding secondary alcohol distills over. By operating the process as described, the water present in the acid solution, either obtained as the aqueous content of the acid employed or which has been added to the acid solution to adjust its acidity, combines with the ester in solution, forming the corresponding alcohol and relatively strong acid. Upon standing, the mixture stratifies due to the limited miscibility of the two components and the layer containing about 75% of the alcohol can be removed without distillation, thus effecting the recovery of the alcohol without danger of its decomposition to the corresponding olefine. As far as we are aware, all the processes as practiced require the distillation of the alcohols from relatively dilute acid solutions, which is not practicable in two respects: (1) because of the substantial decrease in effective yields due to decomposition of the available alcohol and (2) the recovery of dilute acid which must be concentrated for the same or other processes.

If desired, our process can be conducted in a continuous manner by permitting the Stratification of the heated acid solution to take place in a suitable container (which may be cooled by cooling means known to the art) other than that in which the heating of the acid solution is effected and continuously removing the alcohol layer and acid layer. In certain instances, it may be desirable to reintroduce the acid layer into the solution of the ester to modify its acidity and water or relatively stronger acid may be added to the acid layer before or during its introduction, depending on the desired acidity of the solution of the ester. The alcohol layer may be purified by any of the well known methods applicable to the alcohol industry such as rectification, saltingout, etc. The alcohol in the alcohol layer, after neutralization or without neutralization of the small amount of free acid contained therein, may be recovered bydistillation.

The expressions secondary-base and tertiary-base olefines as usedinthe specification and claims, are intended to embrace those olefines which yield secondary and tertiary alcohols respectively on hydration.

While we have in the foregoing'described in some detail the preferredembodiment of our invention and some variants thereof, it will be understood that this is only for the purpose of making the invention more clear and that the invention is not to be regarded as limited to the details of operation described, nor is it dependent upon the soundness or accuracy of the theories which we have advanced as to the reasons for the advantageous results attained. On the other hand, the invention is to be regarded as limited only by the terms of the accompanying claims, in which it is our intention to claim all novelty inherent therein as broadly as is possible in view of the prior art,

We claim as our invention:

1. In the process of producing secondary alcohols from olefines containing more than four carbon atoms, from which tertiary-base olefines have been selectively removed, the'steps of esterifying the secondary-base olefines with a polybasic mineral acid, adjusting the acidity of the resulting acid solution to an acidity less than 35%, heating the solution to a temperature below that at which the corresponding secondary alcohols distill over. permitting the heated acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer. I

2. In the process of producing secondary alcohols from olefines containing more than four carbon atoms, from which tertiary-base olefines have been selectively removed, the steps of sulfating the secondary-base olefines with sulfuric acid, adjusting the acidity of the resulting acid solution to an acidity less than 35%, heating the solution to a temperature below that at which the corresponding secondary alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

3. In the process of producing secondary alcohols from amylenes from which the tertiary-base amylenes have been selectively removed, the steps of esterifying the secondary-base amylenes with a polybasic mineral acid, adjusting the acidity of the resulting acid solution to an acidity less than 35%, heating the solution to a temperature below that at which the secondary amyl alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

4. In the process of producing secondary alcohols from amylenes from which the tertiary-base amylenes have been selectively removed, the steps of sulfating the secondary-base olefines with sulfuric acid, adjusting the acidity of the resulting acid solution to an acidity less than 35%, heating the solution to a temperature below that at which the secondary amyl alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

5. In the process of producing secondary alco hols from olefines containing more than four carbon atoms, from which tertiary-base olefines have been selectively removed, the steps of esterifying the secondary-base olefines with a polybasic mineral acid, adjusting the acidity of the resulting acid solution to an acidity between about 20% to 30%, heating the solution to a temperature below that at which the corresponding secondary alcohols distill over, permitting the heated acid mixture to stratify, removing the alcohol layer from a preponderantly acid layer and recovering secondary alcohol from said alcohol layer.

6. In the process of producing secondary alcohols, from which tertiary-base olefines have been selectively removed, the steps of sulfating the sec- ,1

ondary-base olefines containing more than 4 car-- bon atoms to the molecule with sulfuric acid, adjusting the acidity of the resulting acid solution to an acidity between about 20% to 30%. heating thesolution to a temperature below that at which the corresponding secondary alcohols distillover, permitting the heated acid mixture to stratify, removing the alcohol layer from a preponderantly acid layer and recovering secondary alcohol from said alcohol layer.

7. In the process of producing secondary alcohols from amylene, from which the tertiary-base amylenes have been selectively removed, the steps of esterifying the secondary-base amylenes with a polybasic mineral acid, adjusting the acidity of the resulting acid solution to an acidity between about 20% to 30%, heating the solution to a temperature below that at which the secondary amyl alcohols distill over, permitting the heated acid mixture to stratify, removing the alcohol layer from a preponderantly acid layer and recovering secondary amyl alcohol from said alcohol layer.

8. In the process of producing secondary alcohols from amylene, from which the tertiary-base amylenes have been selectively removed, the steps of sulfating the secondary base amylenes with sulfuric acid, adjusting the acidity of the resulting acid solution to an acidity between about 20% to 30%, heating the solution to a temperature below that at which the secondary amyl alcohols distill over, permitting the heated acid mixture to stratify, removing the alcohol layer from a preponderantly acid layer and recovering secondary amyl alcohol from said alcohol layer.

9. In the continuous process of producing secondary alcohols from olefines containing more than four carbon atoms, from which tertiarybase olefines have been selectively removed, the steps of continuously sulfating the secondary base olefines with sulfuric acid, adjusting and maintaining the acidity of the resulting acid solution below 35%, heating the solution to a temperature below that at which the correspond ing secondary alcohol distill over, permitting the heated acid mixture to stratify and removing the alcohol layer while returning the acid layer to unreacted secondary-base olefines.

1D. In the continuous process of producing secondary alcohols from amylenes, from which the tertiary-base amylenes have been selectively removed, the steps of continuously sulfating the secondary-base amylenes with sulfuric acid, adlusting and maintaining the acidity of the resulting acid solution below 35%, heating the solution to a temperature below that at which the corresponding secondary alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer while returning the acid layer to unreacted secondary-base amylenes.

11. In the continuous process of producing secondary alcohols from olefines containing more than four carbon atoms, from which tertiarybase olefines have been selectively removed, the steps of continuously sulfating the secondarybase olefines with sulfuric acid, adjusting and maintaining the acidity of the resulting acid solution between about to heating the solution to a temperature below that at which the corresponding secondary alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer while returning the acid layer olefines.

12. In the continuous process of producing secondary alcohols from amylenes, from which the tertiary-base amylenes have been selectively removed, the steps of continuously sulfating the to unreacted secondary-base.

secondary-base amylenes with sulfuric acid, adjusting and maintaining the acidity of the resulting acid solution between about 20% to 30%, heating the solution to a temperature below that at which the corresponding secondary alcohols distill over, permitting the heated acid mixture to stratify and removing the alcohol layer while returning the acid layer to unreacted secondarybase amylenes.

13. The process comprising esterifying secondary-base olefines higher than butylene with a polybasic mineral acid, heating the acid solution in the presence of a substantial quantity of water to a temperature below that at which the corresponding secondary alcohols distill over, permitting the acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

14. The process comprising sulfating secondary-base olefines higher than butylene with sulfuric acid, heating the acid solution in the presence of a. substantial quantity of water to a temperature below that at which the secondary alcohols distill over, permitting the acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

15. The process comprising esterifying secondary-base amylenes with a polybasic mineral acid, heating the acid solution in the presence of a substantial quantity of water to a temperature below that at which the corresponding secondary amyl alcohols distill over, permitting the acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

16. The process comprising sulfating secondary-base amylenes with sulfuric acid, heating the acid solution in the presence of a. substantial quantity of water to a temperature below that at which the corresponding secondary amyl alcohols distill over, permitting the acid mixture to stratify and removing the alcohol layer from a preponderantly acid layer.

WILLIAM ENGS. RICHARD MORAVEC. 

